Methought I saw my late espoused saint Brought to me like Alcestis from the grave. (1-2)
With these lines, the poem begins a series of comparisons. Why bother with all the similes? Well, the speaker is trying to describe his dead wife, but he's having some trouble, given then fact that she's not actually around anymore. So first, he compares her to Alcestis, a mythological figure who sacrificed her life for her husband's and was brought back from the underworld by Hercules. He describes Alcestis as "pale and faint," suggesting that his wife, too, appears only vaguely, or perhaps looks sickly, at the beginning of his vision. But hey, since when do ghosts have tans, anyway?
Mine, as whom wash't from spot of childbed taint, Purification in the Old Law did save, […] Came vested all in white, pure as her mind. (5-6, 9)
Based on all this talk of the childbed, we're gonna go ahead and say this woman is not looking her best. In fact, she probably appears downright sickly, which matches up with what we know about how Milton's wife died (in childbirth). But now, she appears all dressed in white, like a woman from the Hebrew Bible who, having recently given birth, has undergone a purification ritual. In this case, her outer appearance matches up with her inner purity. After her death, the boundary between her outer and inner selves has dissolved, so that the state of her soul is fully visible in her physical appearance. Ah, if only that were true in our world. It sure would make spotting bad guys easier.
Mine, […] As such once more I hope to have Full sight of her in heaven without restraint. (5, 7-8)
The speaker says his vision of his wife is like the sight he hopes to have of her "once more," comparing the vision he is having right now to his actual wife as he knew her on earth. So we know for sure now, that his wife is not, say, reincarnated. But if that's the case, then what exactly is she? A dream? A figment of his imagination? A ghost? Is she even there in any real sense if he only thought he saw her?
Her face was veil'd, yet to my fancied sight, Love, sweetness, goodness in her person shin'd So clear as in no face with more delight. (10-12)
Because her face is veiled, the glimpse the speaker is able to get of his wife is not of her physical appearance, but of her "person," a term that indicates the combination of body and soul. By saying her spiritual qualities shine in her person "as in no face with more delight," the speaker suggests that being able to perceive the spiritual qualities of a person is a superior type of vision than being able to make out the physical features of a face. Yeah, that sounds about right to us.